学位の種類: 博士（歯学）. 報告番号: 甲第4145号. 学位記番号: 新大院博（歯）甲第343号. 学位授与年月日: 平成28年3月23日This study aimed to provide an in vitro demonstration that incorporating surface pre-reacted glass-ionomer (S-PRG) fillers into ethylene vinyl acetate (EVA) copolymers, which are used in mouthguards, could be effective in preventing enamel demineralization during mouthguard use. A bovine incisor was cut into enamel blocks. EVA plates containing and lacking S-PRG fillers were formed into eight mouthguards of each type using a thermoplastic material molding device to fit enamel blocks. Mouthguards were attached to each enamel block and immersed in a demineralization solution (37°C, 24 h). The degree of demineralization was assessed by micro-CT. Using the mouthguard lacking S-PRGfiller (control), enamel blocks revealed a major demineralization over a wide area, including areas immediately under the mouthguard, and uncovered areas. In contrast, enamel blocks covered with mouthguards containing S-PRG filler revealed only mild demineralization, both directly under the mouthguard and in uncovered areas. CT values revealed that scores for enamel surfaces at depths from 0 to 252 μm were significantly higher in enamel blocks that were fitted with S-PRG filler mouthguard than in those of the controls (p < 0.05). These results indicate that mouthguards containing S-PRG filler could inhibit demineralization.